Diaboleite
General
CategoryHalide mineral
Formula
(repeating unit)		Pb2CuCl2(OH)4
IMA symbolDbol[1]
Strunz classification3.DB.05
Dana classification10.6.1.1
Crystal systemTetragonal
Crystal classDitetragonal pyramidal (4mm)
H-M symbol: (4mm)
Space groupP4mm
Unit cella = 5.880, c = 5.500 Å, Z = 1[2]
Identification
ColorBlue
Crystal habitAs square tabular crystals, thin plates, massive
CleavagePerfect on {001}
FractureConchoidal
TenacityBrittle
Mohs scale hardness2.5
LusterAdamantine, pearly on cleavages[2]
StreakPale blue[2]
DiaphaneityTransparent to translucent[2]
Density5.41 to 5.43 g/cm3
Optical propertiesUniaxial (−)
Refractive indexnω = 1.980, nε = 1.850
Birefringenceδ = 0.130
Absorption spectraO > E, in thick fragments[2]
SolubilityCompletely soluble in nitric acid
References[3]

Diaboleite is a blue-colored mineral with formula Pb2CuCl2(OH)4. It was discovered in England in 1923 and named diaboleite, from the Greek word διά and boleite, meaning "distinct from boleite".[3] The mineral has since been found in a number of countries.

Description

Diaboleite crystal from a slag occurrence in the Laurium District, Attica, Greece (size: less than 1 mm)

Diaboleite is deep blue in color and pale blue in transmitted light. The mineral occurs as tabular crystals up to 2 cm (0.8 in) in size, as subparallel aggregates, or it has massive habit. Vicinal forms of the tabular crystals have a square or octagonal outline and rarely exhibit pyramidal hemihedralism.[2]

Formation

Diaboleite occurs in manganese oxide ores, as a secondary mineral in lead and copper oxide ores, and in seawater-exposed slag. Diaboleite has been found in association with atacamite, boleite, caledonite, cerussite, chloroxiphite, hydrocerussite, leadhillite, mendipite, paratacamite, phosgenite, and wherryite.[2]

A study in 1986 synthesized diaboleite crystals up to 0.18 mm (0.0071 in) in size using two different methods. The study demonstrated that diaboleite is a low-temperature phase, that is stable under hydrothermal conditions at temperatures less than 100 to 170 °C (212 to 338 °F). At higher temperatures, the first stable mineral to form is cumengeite.[4]

History

In 1923, diaboleite was discovered at Higher Pitts Mine in the Mendip Hills of Somerset, England,[3] and described by L. J. Spencer and E.D. Mountain.[5] The study of the similar mineral boleite was perplexing at the time and this new mineral only compounded the difficulty. As insufficient material was available for a full investigation, Spencer and Mountain named it diaboleite, meaning "distinct from boleite", out of "desperation".[6]

The mineral was grandfathered as a valid mineral by the International Mineralogical Association as it was described prior to 1959.[3]

Distribution

As of 2012, diaboleite has been found in Australia, Austria, Chile, France, Germany, Greece, Iran, Italy, Russia, South Africa, the UK and the US.[2][3] The type material is held at the Natural History Museum in London and the National Museum of Natural History in Washington, D.C.[2]

References

Citations
  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. 1 2 3 4 5 6 7 8 9 "Diaboleite" (PDF). Handbook of Mineralogy. Retrieved June 11, 2012.
  3. 1 2 3 4 5 "Diaboleite". Mindat. Retrieved June 11, 2012.
  4. ↑ Winchell, p. 934.
  5. ↑ Spencer, p. 78.
  6. ↑ Spencer, p. 79.
Bibliography

Further reading

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